Die cast parts and members of aluminum, magnesium and other metallic materials are used extensively in the automotive field and many other applications. Die casting is a process of injecting molten metal into a die casting die. The primary components of a die casting die include cavity blocks that are precisely dimensioned pieces of very hard steel, such as H-13 tool steel or the like. The cavity blocks include interior surfaces machined to the actual shape of the surfaces of the part to be die cast and define an interior cavity representative of the part. One cavity block is generally called the ejector cavity block. Another is called the cover cavity block. The ejector cavity block usually stands "proud", that is, it extends above the parting line surface located between the ejector cavity block and the cover cavity block when "closed" together. The cover cavity block usually includes a depression machined in the steel. When the two cavity blocks are closed together, the molten metal can be injected into the interior of the cavity, to form the die cast part.
The cavity blocks are typically installed in a mold base. A mold base consists of two blocks of steel, usually made from 4140 steel or the like. Each block has a precision pocket machined into it having a size to allow a cavity block to fit therein. The cavity blocks are bolted into each respective "half" of the mold base. The mold base halves have precision holes for receiving precision alignment pins and bushings. After the pins are installed into one half and bushings in the other half, these two pieces can "close" together, aligning the cover cavity block over the ejector cavity block very precisely.
The cover half of the mold base has a large hole through it. This hole is referred to as a "shot" hole. The molten metal is injected through the shot hole. The ejector cavity block has a passage machined in it, called a runner. The runner extends from the cover half shot hole to the interior cavity area, allowing the molten metal to "feed" from the hole to the cavity. After solidification of the metal occurs, the two "halves" are separated or "opened up", exposing the finished die cast part or member. Holes extend through the ejector cavity block to the interior cavity area and pins are operable in the holes to release the cast part or member from the mold. These pins are called ejector pins.
Molded plastics parts and members are also used extensively in the automotive field, and in many other applications. Injection molding is a process of injecting molten plastics material into a mold constructed similarly to a die casting die, as explained above, including mold halves having interior surfaces which define the part surfaces and enclose an interior cavity representative of the part to be molded. When the mold halves are "closed" the molten plastics material is injected through holes into the interior cavity under high pressure and temperature to form the part. After solidification of the plastics material, the mold halves are separated to allow removal of the finished molded part.
In many applications it is highly desirable that the die cast or molded part or member be identifiable as to the time and date it was produced, to give the part or member traceability. Knowing the date of manufacture provides a means to identify a group of parts that may be defective. For instance, they may be the wrong alloy, dimensionally wrong, or produced under improper conditions or the settings required for that particular part. Knowing the date of manufacture also enables identifying what level of revision the part is. Defective designs and dimensionally incorrect parts can fail. Knowing the date or lot of manufacture allows users to identify what parts are defective.
Various devices are known for forming date codes and other traceable information on die cast and molded parts. In the most common devices, limited information is formed on a part. Generally, this information includes only the year and month of manufacture. An example of a common date code device is a cylindrical pin having an end face including a star shape wheel with twelve graduations evenly spaced at 30.degree. apart. One graduation will be distinguished from the other eleven, by being longer to serve as a base line. Generally, this longer graduation represents the month of January. In order to indicate a month, a prick punch is used to produce a small dent or impression in the pin face surface between the graduations, progressing clockwise from the base line indicating the next month, February, then March and so on.
A limitation of this date code device is that someone has to get between the die or mold halves and punch a dent in the next month's space or a monthly basis. This is a problem because the die faces are generally not spaced far apart; they can be as hot as 400.degree. F.; and lighting is almost always very poor. There is also the possibility that the operating mechanism has not been properly locked out on the die casting or molding machine. If the die casting or molding machine is not locked out properly, the machine could close the die or mold halves, crushing the person between them.
There are also other known types of date codes, including pointers or other elements that are manually indexable or rotatable using a screw driver or other tool to indicate a given month. However, these known devices still require someone to place all or a part of his or her body between the die or mold halves. This is dangerous for the reasons discussed above.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.